Railway traffic controlling apparatus



March 19, 1940.

H. A. WALLACE.

RAILWAY TRAFFIC CONTROLLING APPARATUS Filed May 20, 1938 6 Sheets-Sheet l N ME U NbwN WQ J NU m NQN H INVENTOR .wallaee.

' HIS ATTORNEY March 19,1940. H, W L 2,194,371

RAILWAY TRAFFIC CONTROLLING APYARATUS Filed May 20, 1938 s Sheets-Sheet 2 INVENTOR Herbel'z Wallace. BY 6 2 C HIS ATTORNEY March 19, 1940. H. A. WALLACE 2,194,371

RAILWAY TRAFFIC CONTROLLING APPARATUS Filed May 20, 1938 6 Sheets-Sheet I5 k N w n w n i j m N m INVENT R 1 191 110171 allaoe.

0) H18 ATTORNEY March 19, 1940. H. A. WALLACE ,3

RAILWAY TRAFFIC CONTROLLING APPARATUS Filed May .20, 1938 6 Sheets-Sheet 4 v allace INVENTOR HIS ATTORNEY RWNQNNR. I mg U 3% E E F 5 r. RE Q NW WWW F MB wmi 1 g H. A. WALLACE RAILWAY TRAFFIC CONTROLLING APPARATUS March 19, 1940.

6 Sheets-Sheet 6 Filed May 20, 1.938

INVENTOR HIS ATTORN EY til Patented Mar. 19, 1940 UNITED A-res PATENT} OFFICE a. I If. gal-794,371- v RAILWAY 'IRAFFIC conraoume --APPARATUS Herbert L'Wallace, Edgewood, ,Pa., assignor to The UnionfSwitch & Signal Company, Swissvale,- Pa.,'a corporation of Pennsylvania Application May 2d, 1933, Serial No. 209,080

I 44 Claims. (c1; 246-43) My invention relates to railway traific controlling apparatus and it has special referencetothe organization of such apparatus into systems wherein cab signals or other governing devices carried aboard a train vehicle to indicate or enforce the permissible running speed are continuously controlled by energy coded inaccordance with advance conditions and transmitted to the vehicle through the track rails.-

. One object of my. invention is to..provide a novel and improved form of such organization,

Another object is to increase the flexibility, comprehensiveness and range of. applicatiomof train'controlling systems of the-class named.

An additional object is to'extend the number of cab signal indications which are'obtainable from a restricted .varietyof trackway-current codes.

A further object is to accomplish the above by relatively simple additions to and without fundamental changes in the equipment of existing systems of coded cab signalling. 1

In practicingmy invention, I attain the above and other objects and advantages by utilizing track circuit energy of one or another of a number of different carrier wave frequencies (such as and 200 cycles per second), coding or modulating the energy of each of the frequencies so used at one or another of several differentrates (such as 80, and supply circuit interruptions per minute), and providing train carried indicating means which respond distinctively to each different combination of frequency and coding of the trackway current.

I shall describe three representative forms of railway trafiic controlling apparatus embodying my invention and shall then-point out the novel features thereof in claims. These illustrative embodiments of my inventive improvements are disclosed in the accompanying drawings in which: g

Fig. l is a diagrammatic representation of trackway apparatus incorporating my invention and arranged to supply the running rails with coded train control energy having a carrier wave frequency of one value under certain conditions and of a secondvalue under other conditions;

Figs. 2 and} are simplified representations of alternative means for providing train control energy of the second carrier wave frequency which is employed in each of the waysidesystems of Figs.1,6and 8;

Fig. 4 is a diagrammatic view of train carried apparatus organized in accordance with my invention into a five indication eab signalling system suitable forcooperation with and control by the trackway apparatus shown in Fig. 1; v

Fig. 5 is a representation of a modified form of circuits for controlling-the selector relays which are included in each of the train carried equipments of Figs. 4, 7 and 9;

Fig. 6 is a diagrammatic representation of trackway apparatus arranged to supply the running rails selectively with train control energy of two diiferent carrier wave frequencies and extended to code the energy of each .of these frequencies atgthree different rates of supply circuit interruption; l

Fig. 7 is a diagrammatic view of train carried apparatus, organized into a sevenindication'cab signalling system suitable for control by the trackway apparatus of Fig. 6;

' Fig. 8 is a diagrammatic representationof a third form of trackway apparatus embodying my invention and arranged to supply the running rails with coded energy of one or the other of two diiferent carrier wavefrequencies or with coded composite energy of both of those frequencies;

and e Fig. 9 is a diagrammatic view of a third form of train carried apparatus organized into a ten indication cab signalling system suitable for control by the trackway apparatus of Fig. 8.

Inasmuch as my invention contemplates an extension in the number of indications which can be provided by existing systems of coded cab signalling, it will be helpful first to consider the nature and mode of operation of the apparatus which a representative form of such an existing system comprises. as being incorporated in each of the three cab signalling systems of my invention which are represented in Figs. l-4, 6-7 and 8-9. As an introduction to my inventive improvements which. are disclosed herein, description will first be given of the equipment of this illustrative form of existing system in which train control energy of but a single carrier w'a've frequency is utilized.

Considering first the trackway portions of this are included in the showings of each of Figs. 1, 6 and 8. Inallof those figures, the reference characters I and 2 designate the rails of a track over which it will be assumed that traflic moves in the single direction indicated by the arrow, or from Such apparatus is represented :35

single frequency cab signalling equipment, these :45

of track circuit division D, E, F, etc. in conventional manner, as by the aid of a transmission circuit (not shown) extending along the right-of-, way. In the diagrams, characters B and C desi nate power distributing terminals which are sup plied from one such source. To facilitate 6X1 planation it will be assumed that the voltage of this source has a signal power frequency of cycles per second.

Further included in each of the track circuits is the control winding of a track relay TR which is installed at the traffic entering end of the section. Each of these relays is of the alternating current type and, in addition to the control winding which is represented as being directly connected to the track rails, it is provided with a local or exciting winding 5 which receives alternating current energy from the same source as does the track transformer TT at the opposite or exit end of the associated section. When both windings'of the relay are simultaneously energized, the contacts of the relay (represented therebeneath) are actuated to their'uppermo'st or front positions. When, however,'either of the two windings becomes deenergized, these contacts return to their lowermost or back positions.

As-here shown, each of the track circuits normally receives steady energy from the source B-C through a circuit which includes a contact 1 of an approach control relay AR, a conductor 8, and the associated track transformer T1. As long as the track section is vacant, the rails I and 2 thereof transmit this energy to the track relay TR at the opposite end of the section and thereby maintain that relay actuated. When, however, a train occupies the section, the usual shunting action of its wheels and axles deprives the track relay of this steady energy and thereby initiates operations which cause coded energy, suitable for controlling cab signals or other train carried devices, to be impressed between the rails.

The approach control relays AR referred to above are installed at the locations of track section division and each is provided with an actuating circuit which includes a location interconnecting line conductor 9 and a contact 16 of the track relay TR, at the opposite or entrance end of the associated section. Normally each of these relays AR is deenergized by virtue of track relay contact l6 being held in its front p0 ition. When, however, a train comes into the associated track section, the circuit just described supplies the relay with actuating current derived, in the particular arrangement shown, from a direct current control source which is designated by the terminals plus and minus.

At such times the alternating current potential impressed between the rails of the track section is no longer steady but instead is coded" by virtue of the rail supply circuit being interrupted at a definite rate according to the traiiic or other conditions ahead. Such alternate opening and closing of the energy supply circuit is effected at each of the signal locations D, E, F, etc. by a code transmitter there represented at CT. In the illustrative form shown, each of these transmitters is provided with three circuit making and breaking contacts 80, and lBil arranged for selective inclusion in the energizing circuit of the associated track transformer. During operation of the transmitter these contacts are continuously actuatedby a motor or other suitable mechanism (not shown in detail) at three diilerent speeds which, for purposes of explanation, will be assumed to be such as respectively to provide codes of 80, 120 and energy pulses per minute.

Operation of each transmitter is controlled by the associated approach control relay AR, the represented arrangement being such that the transmitter is brought into action only when a train occupies the track section to the rails of which the associated track transformer T1 is connected. When the approach relay becomes actuated, as under conditions of section occupancy, a contact 26 thereof completes a circuit through which the transmitter driving mechanism is supplied withoperating current from the source B--C and by way of a conductor 21. At the same time, contact I of the relay-connects the coding contacts 80, I20 and 80 of the transmitter with the supply terminal B by way of a conductor 28 and thereby conditions these contacts for selective inclusion in the :rail energizing circuit. As long, however, as the relay AR remains unactuated, as when the associated track section is vacant, the two connections named above are broken and contact I of that relay then maintains the tracktransforrhers T'I continuously connected. with the power source terminalsBandC.

Further inctuded in each of the trackway systemsrepresented in Figs. 1, ,6 and 8 are wayside signals S positioned in'the customary manner adjacent the points of track section division D, E. F, etc. These signals are of a type suitable for indicatingto an approaching train the nature of the traflic conditions in the track sections immediately ahead. As represented, each comprises a vertical standard supporting a plurality of semaphore arms one above the other. Elevation of the uppermost arm signifies that the track section immediately ahead of the signal location is clear; elevation of the second arm from the top indicates that there are two clear blocks ahead; elevation of the third arm from the top signifies that the three sections immediately ahead of the signal are unoccupied; and

so on.

Control of each wayside signal S, and also selection of the character of the coded energy supplied to the track section to the rear of that signal, is efiected by a plurality of traffic governing relays H, J I, J2, etc., installed at the associated section division location. These relays are provided with contacts H which are included in actuating circuits for the semaphore arms of the signal and also with contacts 29 which serve, when conditions sorequire, selectively to connect one or another of the contacts 80, I20 and 180 of the coding device CT in the rail supply circuit of the rear track section referred to above. As long as a particulartraflic governing relay is unactuatedi the asociated semaphore arm of the controlled signal S occupies its downward or traffic restricting position. When, however, the relay closes its front contacts, the signal circuit is completed by contact I! and the controlled semaphore arm is then moved upwardly (by apparatus not shown) to an elevated position-which signifies that the associated track sections .inadvance -isclear.

' Thus,- when all'of the traflic governing relays H, J I J2, etc. or energized, the controlled signal S holds all of its arms in the elevated positions and displays the clear indication'which signifies that the several blocks immediately in advance are vacant. Likewise, when all of the relays are deenergized, the signal drops all of its arms and then displays the stop indication which signifies that the block which it directly protects is occupied. Furthermore, when relay H only. is energized, the signal indicates that only one block ahead is clear; when relay J I is also energized, the signal shows that there are but two clear blocks ahead; when relays H, J I and J2 are energized, the controlled signal indicates that there are three clear blocksahead; and so on.

. The code selecting circuits at each signal location, which include contacts 29 of the traflic governing relays H, J I, J2, etc., are rendered effective-only-when the associated approach control relay AR is energized in response to the entrance of a train into the track section to the immediate rear. When, under this condition, relays H and J! are energized, the associated track transformer TT receives energy through a circuit which includes conductor 28, contact I80 of the coding device CT, conductor 32,-the relay contacts 29 and conductors 3| and 8. This causes the rails of the track section tothe immediate rear to be supplied with energy of the 180 code. I When relay H only is energizedfthe track transformer circuit includes coding contact I20 and conductor 33 and the .track circuit is then supplied with energy of the 120 code. Finally, when relays H and J I are deenergized, energy of the 80 code is supplied to the trackway through a circuit which includes coding contact 80 and conductor 34. The represented actuating circuits for the traffic'governing relays H, J I, J 2, etc. at each signal location receive energization from the before referred to direct current source designated by terminals plus and minus. Respectively included in all of these circuits are the contacts III, II, I2, etc. of the track relay TR at the same location. Further included in the circuit for relay J I is a location interconnecting line conductor 2| and contact I 0 of the track relay at the next location in advance; in that for relay J2 is a line conductor 22, contact I I of the track relay at the first location in advance, the line conductor 2| extending forward from that location and contact I 0 of the track relay at the second location ahead; and so on. Similarly, the actuating circuit for each of the relays J3 of Figs. 6 and 8 includes contact I3 of relay TR at the same location, line conductor 23, contact 12 of relay TR at the next location in advance, line conductor 22, contact II of relay TR at the second location in advance, line conductor 2|, and contact III of relay TR at the third location in advance.

In operation of the wayside signal control and coded energy supply system which has just been described as forming a part of the trackway apparatus of each of Figs. 1, 6 and 8, when all ofthe sections of the protected stretch of track I2 are unoccupied, the track relay TR at each of the several signal locations is picked up, all of the relays H, J I, J2, etc. in each of the associated trailic governing groups are picked up, and all of the approach control relays AR are dropped out. In consequence, all of the wayside signals S give unrestrictedly clear indications which signify that thet-several 'blocks immediately in advance of each are unoccupied and all of the track transformers TT receive steady energy from the supply source BC.

' As, now, a train advances through the stretch, the shunting action of its wheels and axles causes the track relay TR associated with each section occupied by it to release. This opens all of the trafiic governing relay circuits which are carried through the contacts of that relay and also completes the circuit for the approach relay AR at the next location in advance. As a result, all of the relays H, J I, J2, etc. at the location of this unactuated track relay become deenergized, the associated wayside signal S indicates that the block which it directly protects is occupied, and the coding device CT at the advance location is brought into operation. It then codes the energy supplied to the rails of the occupied section at a rate which is determined by the condition of the associated traffic governing relays.

At the entrance of the first vacant block to the rear of the above-mentioned train, relay H only is energized, relays J I, J2, etc. are deenergized and the signal S controlled thereby indicates that there is only one clear block ahead; at the entrance of the second vacant block behind the occupied one, relay J2 and remaining J relays of higher numeral suffix are deenergized and the controlled signal indicates that there are two clear blocks ahead; and so on.

If the several sections ahead of the referred to train are vacant, the traflic governing relays H, J I, J2, etc. at the location immediately in ad- Vance of that train assume positions in which their selector contacts 29 include coding contact I80 in and exclude contacts I20 and 88 from,

the supply circuit of the associated track transformer TT. Under these conditions, the energy supplied from source BC to the rails of the occupied track section is interrupted at the rate of 180 times per minute. In the event that a section comparatively close ahead is occupied by a second or advance train, the selector contacts 29 of the trafilc governing relays just referred to include coding contact I20 in the track transformer supply circuit. This causes the energy which is transmitted to the rails of the section occupied by the following train to be interrupted at the rate of 120 times per minute. Finally, if a still closer section is occupied by the advance train. the contacts 29 include coding contact 80 in the trackway circuit, and the energy supplied to the rails of the section which the following train occupies is then interrupted at the rate of 80 times per minute.

Before considering the invention added portions of the trackway apparatus of Figs. 1, 6 and 8, the existing system portions of the cooperating train carried equipments of Figs. 4, '7 and 9 will first be described.

E&Ch of these equipments converts a measure of the coded energy present in the track rails I and 2 into appropriate train controlling indications aboard the locomotive or other train vehicle'which carries the equipment. In the representative form shown, the single frequency responsive portions of the apparatus of each of Figs. 4, 7 and 9 include a receiver 3'l--38, an amplifier 40, a master or code following relay MRI, a decoding transformer DT, decoding relays DR, an indication giving cab signal CS, a warning whistle W, an acknowledging switch 45-45, and acknowledging relay P.

Control energy from the running rails I2 is a second capacitor 44.

transmittedto the train carried apparatus. by the receiver. In the form shown,- it consists of a pair of windings 31 carried on a laminated iron bar 38 which is mounted ahead of the advance truck of the equipment carrying vehicle just above and spanning the two rails. These elements constitute the core and the secondary of a transformer of which the rails are the primary and when alternating current flows in the rails voltages are induced in and additively combined by these windings 31.

The amplifier 40 is controlled by the combined output potential of the receiver windings and it, in turn, delivers an appropriately increased amount of actuating energy to the master relay MR1. The simplified form of amplifier shown utilizes an electronic tube 39 and a. master relay transformer 4|. The secondary winding of this transformer is connected to the operating winding of relay MRI; the primary winding is included in a circuit through which a high voltage direct current source, designated by the terminals +11. and -h, passes current from the anode to the cathode of the tube; and the receiver output potential is impressed between the grid and cathode of the tube.

When no current is present in the track rails ahead of the equipment carrying vehicle, or when unvarying alternating current flows therein, the

tube grid potential is such that the flow ofunidirectional current through the primary of transformer 4| is constant. Under such circumstances no energy is transmitted to relay MRI. When. however, the rails carry coded or periodically interrupted alternating current, the tube 39 alters its impedance in step with the pulses of this trackway energy. This, in turn, causes the transformer 4| to impress an alternating potential of the code rate frequency (80, 120 or 180 cycles per minute for the apparatus shown) upon the actuating winding of the master relay.

Interposed between the receiver and the amp ifier is an electrical filter Ql represented as including a first capacitor 42, a reactor 43 and The elements of this filter are so interconnected and proportioned as to suppress all frequencies except that of the cycle or other selected carrier wave value. This makes it impossible for the master relay MRI to respond to trackway energy having a carrier wave frequency differing substantially from the selected value above mentioned and thus renders the apparatus immune to interference from foreign currents.

The master relay MR1 follows the coding of the energy which the windings 31 receive from the track rails. As shown, it is of the direct current polarized type and has a contact 41 which shifts from one position to the other when the polarity of the relay energization changes and which, when the relay is unenergized', stays in the position to which it was moved by the last energization of the relay. In the particular arrangement represented, this contact is moved to its left-hand or energy on position (shown dotted) at the beginning of each pulse of trackway energy (at which time the operating winding of the relay receives a "positive half cycle of current from transformer 4|), and at the end cf each trackway energy pulse (at which time the relay winding receives a negative half cycle of current) the contact is returned toits righthand or "energy off position (shown heavy) where it remains until another pulse of energy appears in the trackway. Thus, the contact occupies its left-hand positiondurlng each on period of the trackway code and its right-hand position at all. other times including the off code periods.-

-Energization of the decoding transformer DT is controlled by this contact 47 of the master relay.. When following the'trackway code, it pole changes a circuit from which the primary windingx of the transformerreceives pulses of directcurrent at code-frequency; Ordinarily this current supplied to the transformer energizing circuit from the 32 volt headlight genera-tor of the locomotive or other suitable direct current source designated in the diagrains by the terminals plus and minus. .Also included in the particular circuit shown are contacts '48 and 49 of a selector relay FSI later to be described. As long as the master relay MRI is following-a trackway code,- these "contacts fhowever,f'contact" 41. isv shifted to its left-hand or energy on. position, the ,flowof current is by 'waiyof ,jconductor' 52-and then is downwardly hrough, the upper half of the transformer P y, v

The resulting code frequency pulses of primary current induce inthe secondary. winding of the decoding transformer DT an alternating current voltage of a frequency whichils the same as is that of 'the trackway code by which the pulses are initiated. Thus, this secondary voltage will, in each of the particular systems disclosed, have a frequency of 80, or cycles per minute. It supplies actuating current to the three decoding relays DR through frequency selective circuits 54. 4

These deco-ding relays DR control the cab signal CS. As represented they are of the direct,-

current type and each has a pair of signal control contacts 63 and 64 which are quick acting in both the pick-up and drop-out directions. When the relay is deenergized, these contacts occupy their lowermost or back positions and when the relay receives suflic ent energizing current to effect its actuation they are biased to their uppermost or front positions.

In the arrangement shown, a full wave rectifier 55 is included in the circuit through which each of the relays DR receives energizing current from the decoding transformer DT. In the case of relay DRH, the rectified supply circuit includes a reactor 56 and is responsive to coded energizing pulses having frequencies corresponding to all three of the named 80, 120 and 180 trackway codes. In the case of relay DRI 20, the supply circuit includes a capacitor 51 and a reactor 58 which are so interrelated as to pass enough current to actuate the relay only when energizing pulses of the 120 code frequency are received from the transformer DT. In the case of relay DR! 80, the circuit includes a capacitor 6! and a reactor 2 designated to be resonant at the 180 code frequency and to energize the relay only when the decoding transformer passes energy pulses at the rate of 180 per minute.

' In operation of the decoding equipment just described, all three of the relays DR remain dropped out when the train carried apparatus receives uncoded steady energy or no energy at all; relay DRH only is picked up when the energy received from the trackway is of the 30 code; relays BBB and DRIZU are both picked up when the. received energy is of the 120 code; and relays DRH and DRIBO are picked up and relay DR! 2!] is dropped out when energy of the 180 code is received from the track rails.

A distinctive indication on the part of the cab signal CS is produced by each one of the four just described positional combinations of the decoding relays DR. This train carried signal may, of course, be of any suitable type adapted to in dioate the track conditions ahead by means of color light, position light or other aspects within the engine cab. As illustratively shown at CS, it consists of four electric lights 5,15, 50 and A arranged to be energized selectively. To facilitate description, it will be assumed that, when lighted, these lamps respectively display the characters by which they are marked in the diagrams and that the resulting signal aspects are interpreted by the engineman to mean that the maximum permissible running speed is 5, 15, 50 or an Authorized maximum number of miles per hour.

For supplying lighting current to the lamps, use is made of the locomotive headlight generator or other source designated in the diagrams by the terminals plus and minus. Included in and serving to control the lamp energizing circuits are the previously mentioned contacts 63 and 64 of the decoding relays DR.

When all three of these decoding relays DR are dropped out, as when the signal carrying train goes into a track section already occupied by another train, cab signal lamp 5 is lighted. Its energizing circuit extends from the positive supply terminal, through the back contacts 63 of all three decoding relays in series, conductors 66 and 61, the lamp 5, conductor 68, and the back contacts 64 of all three relays DB in series back to the negative supply terminal.

When relay DRH only is actuated, as when the signal carrying train is in an otherwise vacant track section which is close behind a section occupied by another train ahead, cab signal lamp' i5 is lighted. Its energizing circuit may be traced from the positive supply terminal, through back contacts 63 of relays DRIZD and DRIBK! in series, front contact 63 of relay DRH, conductors 69 and 10, the lamp I5, conductor 1|, front contact 64 of relay DRI-I, and back contact 64 of relays DRIZD and DR|80 in series back to the negative supply terminal.

When relay DRIZO is actuated, as when the signal carrying train is in a track section further removed from an occupied section in advance, cab signal lamp 5!! is lighted. Its energizing circuit extends from the positive supply terminal through back contact 63 of relay DRl8ll, front contact 63 of relay DRIZI), conductors l2 and 14, the lamp 50, conductor 16, front contact 64 of relay DRI20 and back contact 64 of relay DRISE) back to the negative supply terminal.

Finally, when relay DRiBfl is actuated, as when the signal carrying train is in a track section so far removed from an occupied section in advance as to make full or authorized speed safe, cab signal lamp A is lighted; Its energizing circuit may be traced from the positive supply terminal throughfront contact 63 of relay DRI80, conductor l8, the lamp A, conductor 8|, and front contact 64 of relay DRAW back to the negative supply terminal.

Further forming a part of each of the train carried equipments represented in Figs. 4, '7 and 9 are the customary means for supplementing the visual indications given by the cab signal CS by an audible warning which sounds whenever the signal indication changes in the more restrictive or speedreducing direction. In the arrangement shown, this warning is emitted by a whistle W which upon being placed in operation continues to blow until the engineman proves his alertness by acknowledging the change in indication which initiated the blowing. Such acknowledgement is efiected through the agency of a switch l546 which, together with contacts of a group of acknowledging relays P, is included in circuits for controlling the whistle operation.

The particular whistle shown at W is sounded by compressed fluid, such as air from the usual brake operating pressure system, supplied thereto from a conduit 82 through an electrically operated valve 83. Normally this valve receives closing current, from the direct current terminals plus and minus, through a circuit which includes front contacts 15 and 85 of the acknowledging relay P55 (P60 in Figs. '7 and 9) and blade 46 of the acknowledging switch. This current keeps the whistle silent. When, however, the circuit just described is interrupted, the valve opens and allows compressed air to pass into and operate the whistle.

The blades of the acknowledging switch 45-46 are normally held, in the represented upwardly biased positions by a compression spring 8!]. To silence the whistle following a more restrictive indication change, the engineman depresses these blades and holds them in their downwardly biased positions for a short time interval. Blade 46 then opens the whistle control circuit while blade 45 initiates actuating operations on the part of the acknowledging relays P.

These acknowledging relays are arranged to be operated in a given sequence of which relay P5 marks the beginning and relay P50 (P60 in Figs. 7 and 9) the ending. As shown, each relay in the acknowledging group has a pick-up" winding 85, a stick winding 87, and a contact 88 which controls the stick circuit of that relay. All relays except the highest sequence device also have a contact 84 which controls the pick-up circuit for the next relay in the operating sequence. In place of contact 84 that highest sequence relay is provided with the before referred to contacts l5 and 85 which form a part of the silencing circuit for the whistle W.

Current for energizing the referred to pickup and stick circuits is obtained from the terminals plus and minus of the same direct current source that supplies lighting current to the cab signal lamps. In the case of each relay, when neither of its two windings 8t and 8'! is energized, the relay contacts occupy their lowermost or unactuated positions. When, however, energizing current is supplied to either or both of the two windings, the relay contacts are picked up. All of these acknowledging relays P, moreover, are sufficiently slow releasing as not to drop out their contacts within the short interval of time which is required by the decoding relays DR to shift their contacts from one position to the other in efiecting a change in cab signal indication.

In the particular arrangement of pick-up and stick circuits represented, relay P5 receives pickup current (through its winding 87) when blade 45 of the acknowledging switch is depressed and stick current (also through its winding 8'!) by way of its own front contact 88 when closed if at that time signal lamp 5 is energized over conductor 57; relay Pl5 receives pick-up current (through its winding 86) by way of front contact 84 of relay P5 when closed and stick-current (through its winding 81) by way of its own front contact 88 when closed if signal lamp I5 is at that time energized over conductor 10; and so on.

In operation of the acknowledging equipment, the whistle W normally remains inactive, as has already been pointed out, by virtue of its silencing circuit being completed through front contacts l5 and 85 and switch blade 45. In the event, however, of a change in indication in the more restrictive direction, this circuit becomes interrupted, the warning whistle is brought into action, and the switch 45-45 must be operated to restore the acknowledging relays P to a condition in which the circuit may again be completed to silence the whistle.

For example, assume that cab signal lamp A is lighted in response to decoding relay DRISO being actuated, which is the normal or clear ad vance track condition. In this situation, all of the acknowledging relays P are deenergized and released by virtue of all of their pick-up and stick circuits being interrupted, and the back contacts 15 and 85 of relay P55 (P60 in Figs. '7 and 9) complete the whistle silencing circuit. That circuit extends, under these conditions, from the positive supply terminal, throu h front contact 63 of relay DRiilEl, the lamp energizing conductor l8, conductor 7e, back contact 75, conductor 92, switch blade 46, conductor 93, the valve 83, back contact 85, conductor T1, the negative lamp energizing conductor BI, and front contact 66 of relay DR| back to the negative supply terminal,

If in response to decoding relay DRiSfi dropping out and relay DRiZEl picking up lamp A goes out and lamp 50 is lighted, the whistle starts to operate. This results from a disconnection, at contacts 63 and 64 of relay DRlSD, of the energizing source from the circuit just traced. As the engineman depresses the acknowledging switch preparatory to silencing the whistle, blade 45 thereof completes the pick-up circuit for relay P5 and the acknowledging relays P5l5-50 are, as a result, actuated in the order named. (Also energized along with relays P5l550 is an added relay P35 which is included in the extended system of my invention that is represented in Fig. 4 and which is more fully described in a later portion of this specification.) Through stick current now received from the conductor 74 which energizes lamp 50, relay P50 locks itself in the picked-up position, and front contacts 75 and of that relay now connect the whistle silencing circuit with the supply terminals plus and minus which are represented directly above these contacts. As the acknowledging switch later returns to its normal position, relay P5 drops out and causes the pick-up circuit of each of the other acknowledging relays to be opened. All of the acknowledging relays drop out except P50 the stick circuit of which is closed from conductor 14 and through its front contact 88. At the same time, blade 46 of the switch completes the whistle silencing circuit and thereby discontinues th warning sound. r

If in response to decoding relay DR|20 dropping out, lamp 50 goes out and lamp i5 is lighted, the whistle is again operated. This results from a breaking at contact 63 of relay DRIZ!) of the stick circuit for relay P50 and the consequent disconnection, at contacts 15 and 85 of that relay, of the whistle silencing circuit from the energizing terminals above referred to. As the acknowledging switch SL-46 is depressed, relays P5i5--50 are again picked up in order. Relay Pl5 now looks itself in from stick current received from the conductor 10 which supplies energy to the lamp l5. Relay P50, in turn, is now also maintained actuated and contacts 15 and 35 thereof silence the whistle as soon as the switch d5-46 later returns to its normal position. At that time acknowledging relay P5 is allowed to drop out.

If in response to decoding relay DRH dropping out, lamp 15 goes out and lamp 5 is lighted, the whistle W once more operates. This results from a breaking, at contact 63 of relay DRH, of the stick circuit for relay P45; the dropping out of relays Pi5 and P50 which follows; and the before explained opening, at contacts 75 and 85 of relay P50, of the whistle silencing circuit. As the acknowledging switch is depressed, all of the relays P are once more picked up in order. Relay P5 now looks itself in, by connection with the conductor 6'! which supplies current to the lamp 5, and thus holds the remaining acknowledging relays also picked up. Contacts 15 and 85 of relay P50 now set up the whistle silencing circuit and cause the whistle to cease operating when the switch 45-46 later returns to its normal position. Relay P5 does not, however, now drop out because its stick circuit is now completed by way of its front contact 88 and conductor 6?.

Changes of cab signal indication in the speed increasing or less restrictive direction do not produce operations on the part of the warning whistle W. This is because each indication change of that character is accompanied by the completion of the stick circuit for the next relay P in the acknowledging sequence. As has been indicated, these relays are sufficiently slow releasing as not to drop out during the short interval of time that the decoding relays require to shift their contacts in eifecting each less restrictive indication change. In consequence, each of such changes allows only the relays below it in the acknowledging sequence to drop out and keeps all of the acknowledging relays above it in the sequence picked up. As a result, contacts 75 and 65 of the whistle silencing circuit are maintained in their front positions during those changes and the whistle W is prevented from operating until a more restrictive indication occurs.

In the thus far described portions of each of the three cab signalling systems of Figs. 1-4, 6-7 and 8-9 use is made of track circuit energy of but one carrier wave frequency, assumed to be cycles per second and shown as being supplied from source B-C. When coded at the illustrative rates of 180, and 80 rail supply circuit interruptions per minute, this energy respectively causes the cab signal OS to display the indications of A, 50 and 15; when this energy is uncoded or is not present in the track circuit, the signal is caused to display indication 5.

The apparatus so far described thus corresponds to that used in a four indication system of con- 'ventional character. In many applications such as a limited number of indications is not sumcient to take care of additional train control requirements which recently have come to be regarded as desirable. Typically the wayside portions of these existing installations made provision (including transmitters CT) for coding the trackway current at a limited number of rates only, such as the three above named, and the train carried portions thereof likewise provide correspondingly restricted decoding apparatus (including relays DR). Supplemental means for extending the cab signal indications obtainable from a restricted variety of trackway current codes to a number suflicient to meet all possible train control requirements are, therefore, needed.

In order to supply this particular need and generally to provide a cab signalling system of practically unlimited flexibility, comprehensiveness and range of application, I propose, as was stated at the beginning of this specification, toutilize trackway energy of more than one carrier wave frequency and to code or modulate the energy of each of the frequencies thus selectively used at one or another of the several different rates now customary or already provided for in existing installations. As will be seen presently, this proposal permits the present wayside coding devices CT and the present train carried decoders of existing installations to be used without fundamental modification and requires that supplements be made only to the apparatus and circuits of those wayside sections or blocks which must transmit the additional indications and only to the train carried equipments which need to receive them.

Three representative manners in which the above stated proposal may be carried into practice are disclosed by Figs. 1-4, 6-7 and 8-9. In all of these embodiments of my invention the added indications are obtained by the making of relatively simple additions to and without fundamental changes in the equipment of the conventional system of cab signalling already described as being of the four indication variety.

Five indication system of Figs. 1-4

The typical four indication cab signalling system just referred to as being controlled by single frequency trackway energy makes use of all of the wayside apparatus represented at locations D and F of Fig. 1. At location E, however, I have additionally shown supplemental trackway equipment by means of which one added indication may be provided for in the train carried apparatus of Fig. l. The arrangement of this supp-lemental equipment is such that at certain times it supplies the track rails with coded train control energy of a carrier wave frequency which differs from the assumed cycle value of source B-C.

The referred to energy of this second frequency may be derived from any suitable alternating current source and distributed to the various section dividing locations requiring it in any suitable manner, as by the aid of a second transmission circuit (not shown) extending along the rightof-way. In Fig. 1 (and in Figs. 6 and 8 also) characters B2 and C2 designate power distributing terminals which are supplied from one such source. If desired, the second frequency potential appearing between terminals B2 and C2 may also be generated locally by means of apparatus of the character shown in Figs. 2 and 3 (later to be described).

The frequency of this supplemental energy may be of any value which differs suificiently from that of the first source B-C and from interfering harmonics of commercial current frequencies to be clearly distinguishable therefrom by the train carried apparatus which it controls. One such frequency value suitable for the application under discussion is 200 cycles per seconl. To clarify description, it will be assumed, throughout the remainder of this specification, that the voltage appearing between terminals B2 and C2 has a frequency of that representative order.

In the organization of equipment shown at location E of Fig. 1, use is made of a transformer 260T to transmit energy from this second source BEL-02 to the trackway coding circuit under those preselected conditions already referred to. In the illustrative arrangement represented at location E, these particular conditions are refiected by the positions of a contact '53 of the trafiic governing relay H and of contacts 102 and HM of the approach control relay AB.

The traific governing relay contact '53 is interposed between the coding contacts 8!! HIE-I89 of the transmitter CT and the two supply sources of train control energy. It serves to select Whether coding circuit conductor 28 receives 100 cycle energy from source B-C through contact 7 of relay AR and a conductor Hill, or 200 cycle energy from source Bil-C2 through contacts Hi2 and Hit of relay AR, transformer 290T and conductor I83.

The former selection is made in accordance with those traific conditions which involve occupancy by a train of one of the track sections beyond or in advance of location E. Depending upon the remoteness of such a train ahead, the rails of track section B-E are supplied, in the manner previously explained in detail, with 100 cycle energy coded at the rate of 180, or 80 circuit interruptions per minute in the event that a train from the rear comes into the section named.

Selection of energy from source BZC2 for supply to the trackway may, of course, be made in any additional special manner desired. For purposes of illustration, Fig. 1 shows this selection as being determined by a curve or other permanent speed restriction within track section D-E where it is there so marked on the diagram. To simplify explanation, it will be assumed that 35 miles per hour is the maximum speed at which a train may safely proceed through this particular portion of the section DE.

In the further interests of description clarification, it will also be assumed that when only one section ahead of any of the non-curve con taining blocks, such as E-F, is vacant, as reflected by traffic governing relay H only at the entrance thereof being actuated, the permissible running speed within that block is 50 miles per hour; and that when the section immediately in advance of any one of the sections of the protected track stretch of Fig. l is occupied, as reflected by relay H at the entrance thereof being dropped out, a speed of 15 miles per hour through that section should not be exceeded.

When, now, a train comes into section D-E the associated relay TR drops its contacts, thereby completing (at [6) the actuating circuit for the approach relay AR at location E, contact 26 of that relay places code transmitter CT in operation, contact '5 thereof interrupts the steady energizing circuit (which includes conductor 8) for the transformer TT at location E and connects conductor I00 with supply terminal B,

and contacts I92 and lfi l con ect transformer 2361 to the supply source B2C2.

If one or more track sections in advance of D-E is vacant, relay at location E will be picked up. Contact 73 of that relay then connects coding circuit conductor 28 to 290 cycle supply conductor and maintains it disconnected from 10G cycle supply conductor IUD. Under these circumstances, transformer 285T supplies the rails of section D-E with 2% cycle energy derived from source B2C2. Contact I29 of transmitter CT now codes this energy and track transformer ".T'T transmits it to the rails in the usual manner. The circuit through which this thus coded 20G cycle energy is supplied to the track transformer now extends from one side of the secondary of transformer 2651, through conductor 303, front contact E3 of relay conductor 28, coding contact E26 of trans-nutter CT, conductor 23, front contact 29 of relay conductors 3i and 8, the primary winding of transformer T2, and conductor E06 (common to both of the transformers TT and 2391') back to the other side of the secondary of transformer BUST. In the cooperating apparatus of Fig. 4 (carried by the train within section D-E and presently to be described), this 200 cycle track circuit energ" of the i251 code causes the lamp of an added cab signal unit CSa to light and thereby indicate to the engineman that a speed of 3-5 miles per hour should not be exceeded.

As long as the train remains in the section D-E containing the curve or other permanent speed restriction, it is desired that neither of the lamps 5G or A of signal CS ever be lighted to authorize a hi her speed even though the track ahead may be vacant for a long d stance. For this reason no use is made at location E of the high speed authorizing coding contact Hill of the euipment there represented.

If the track section E-F immediately ahead of section 13-151 is occupied, traflic governing relay H will be dropped out. Contact '53 of this relay now connects coding circuit conductor 28 to 100 cycle supply conductor i 39 and maintains it disconnected ircm 2S0 cycle supply conductor H73. When, now, a train is in section D-E, source B-C supplies th rails of that section with 100 cycle ene1 -.y coded by contact 8% of the transmitter CT and through a circuit which may be traced from supply terminal B through front contact "I of relay AR, conductor on, back contact T3 of relay H, conductor 28, coding contact Bd of transmitter CT, conductor back contact 25% of relay H, conductors 3! and S, and the primary winding of transformer T1 back to supply terminal C. In the manner previously explained, this 100 cycle track circuit energy of the Si) code causes the lamp l5 of cab signal CS to light and thereby indicate to the engineman that a s eed of 15 miles per hour should not be exceeded.

When employing multi-frequency trackway energy in the manner represented at location E, provision is made for at all times supplying the local or exciting winding 1: of the track relay S: to the immediate rear, or at location I) in the diagram of Fig. l, with energy of the same character as is that impressed upon the track transformer T1 which supplies the rails of the intervening section, or DE in the diagram. This provision takes the form of a line conductor E65 which connects the relay winding directly with the translormer primary supply conductor 8 at location Regardless now of whether the energy supplied through transformer T1? at that location to the rails of section D-E and by them to the control or track winding of relay TR at location E is of the 100 cycle variety from source B-C or of the 200 cycle variety from source Bil-C2, the exciting winding 6 of that relay simultaneously receives energy of the same frequency through line conductor Hi5. This permits energy from either of the sources named to picl: up the tr ck relay at location D and otherwise assures the proper functioning of that relay under all possible operating conditions of the multi-freeuency equipment at location E.

Further regarding the facilities for supplying energy of the second carrier wave frequency explained as appearing between terminals B2 and C2, it has already been mentioned that this energy may be generated locally at each of the track section division locations where required. VVhc-n this second frequency is of the assumed value of 200 cycles per second, the apparatus of Fig. 2 may be employed with advantage for the purpose named.

in the arrangement of Fig. 2, the second frequency energy is obtained more or less directly from the 100 cycle supply source BC, a full wave rectifier 588 being interposed between the transformer 298T and that source. When energized by this 100 cycle voltage the rectifier causes recurr'ng pulsations of unidirectional voltage in the number of 200 per second to appear between its output terminals, with which conductors m8 and ill": respectively connected. Each one of these pulsations is produced by each half wave of the rectifier supply potential and it, in turn, circulates through the primary winding of transformer ZUFJT a unidirectional current which first builds up from zero to a maximum and then again decreases to zero.

In consequence, the alternating electromotive force induced in the secondary winding of that transformer has a frequency which is double that or" the 100 cycle rectifier supply potential. This comes about from the fact that each build up of primary current in the transformer 288T produces a positive half cycle or secondary voltage and each decrease in primary current which follows similarly produces a negative half cycle of voltage in the secondary winding.

When the 2.09 cycle energy is supplied in the manner just descrioed, the approach relay contacts I02 and We, used by the arrangement of location E of Fig. 1, may be dispensed with and the control circuits shown in Fig. 2 for the rectifier H38 substituted therefor. These include the contact of the approach rclay AR and a conductor ll i. As long as the track section with which the supply apparatus of Fig. 2 may be associated is vacant, the represented 200 cycle generating apparatus is unenergized. When, however, a train comes into that section, contact I connects the rectifier with source B-C and places transformer 2&6? in a condition for supplying the rails 01 that section with 200 cycle energy by way of relay contact 73 and conductor 23.

Energy of the second carrier Wave frequency may also be generated locally by means of the tuned reed alternator shown in Fig. 3. In the arrangement of that figure transformer 268T receives primary energizing current, from a direct current source designated by the terminals plus and minus, through a circuit which is periodically interrupted by a reed type vibrating member H2. Typically, this reed is of iron or other magnetic material and oneend thereof is rigidly fixed to a suitable stationary support. Moreover, the reed has a natural rate of vibration which corresponds to the desired frequency of the output voltage of transformer 200T.

Driving movement is imparted to the reed by an electromagnet II3 the energizing circuit of which is completed at point H4 each time that the reed approaches its lowermost position and thus the vibration is maintained as long as this driving circuit is supplied with energy. When in its lowermost position the reed sets up a circuit through which current flows by way of conductor I II] upwardly through the lower half of the primary winding of transformer 209T to mid tap II5; when in its uppermost position the reed completes a similar circuit through which current flows by way of conductor I09 downwardly through the upper half of the transformer primary and to the negative supply terminal, also by way of mid tap I I5.

Each complete vibration of the reed thus causes a cycle of alternating current voltage to be induced in the secondary winding of the transformer and in this manner an electromotive force corresponding to that of source B2-C2 is generated whenever approach relay AR actuates its contact I02 to the upward or front closed position. Because of the greater flexibility, which permits energy of a frequency value which is not necessarily a multiple of that of source BC to be produced, this tuned reed alternator will in many instances be found especially useful.

Comparable flexibility may, of course, also be obtained by employing a small motor generator set or other equivalent means to provide the second frequency energy now under consideration. Such means, as well as the expedients of Figs. 2 and 3, may be used to take the place of the supply source terminals B2 and C2 in each of the wayside systems of Figs. 1, 6 and 8.

Returning now to the complete system of wayside apparatus represented in Fig. 1, it will have become apparent that this equipment operates to supply the track rails selectively with train control energy derived either from source BC (assumed to be of 100 cycle per second frequency) and coded at 180, 120 or 80 supply circuit interruptions per minute or v derived from source B2-C2 (assumed to be of 200 cycle frequency) and coded at the rate of 120 circuit interruptions per minute. As has already been explained, the first frequency or 100 cycle energy causes the cab signal CS of the cooperating traincarried equipment of Fig. 4 to give one or another of the four indications A, 50, 15 and 5. In order that this equipment may also respond to the second fre quency or 200 cycle energy and thereby display a fifth indication, I supplement the conventional four indication portions thereof by certain additional apparatus which will. now be described.

As shown in Fig. 4, this added apparatus comprises the before referred to cab signal CS1! for displaying the fifth indication, an acknowledging relay P for that signal, a pair of selector relays FSI and F52 for at times transferring the control of decoding relays DR from the main cab signal OS to the added signal CSa, a master or code following relay MR2 for assisting master relay MRI in controlling the two selector relays, and a filter Q2 for transmitting to master relay MR2 train control energy of the second carrier wave frequency only.

As represented, the added master relay MR2 is a duplicate of the first master relayMRI which follows the coding of 100 cycle trackway energy. Actuating current is delivered to this second relay by an associated amplifier a, which, like the first amplifier 40, is controlled by potential inductively picked up from the track rails I and 2 by the receiver windings 37. Such control potential, when of the proper character, is transmitted to the grid circuit of amplifier 40a by the filter Q This second filter is represented as being of the same character as the filter shown at QI in association with relay MRI. It differs, however, in that its elements 42a, 43a and 44a are so proportioned as to suppress all frequencies except 1 that of the 200 cycle or other selected second carrier wave value. In consequence, the master relay MR2 responds only to trackway energy having a carrier wave frequency of that second value.

Operation of the added master relay MR2 by 200 cycle trackway energy is the same as that of the first master. relay, MRI by 100 cycle energy. During the off periods of the trackway code, contact 41 thereof occupies its right-hand or energy off position and during each on code period of 200 cycle trackway energy this contact is held in its left-hand or energy on position.

The selector or control transferring relays FSI and FSZ are respectively associated with, and controlled by, the code following relays MRI and MR2. Each is provided with contacts which are Actuating current for these selector relays FSI and F32 is selectively transmitted to'the operating windings thereof through circuits which are respectively controlled by the two master relays MRI and MR2. In the arrangement shown, this,

current is supplied from the direct current source identified with the terminals plus and minus. Included in the actuating circuit for relay FSI is the contact II of relay MRI and conductor 52 and in that for relay FS2 is the contact 41 of relayv MR2 and a conductor IIB.

Whenever the master relay MRI shifts its contact to the left-hand position, as during each "011 period of coded 100 cycle trackway energy, selector relay FSI thus receives actuating current through a circuit which extends from the positive supply terminal, through left biased contact 4'! of relay MRI, conductor 52, and the Winding of relay FSI back to the negative-supply terminal. When, and as long, however, as master relay MRI holds its-contact in the right-hand position, selector relay FSI remains unenergized and unactuated. v

Likewise, whenever master relay MR2 shifts its contact to the left-hand position, as during each on period'of coded 200 cycle trackway energy, selector relay FS2 receives actuating current through a comparable circuit extending from the positive supply terminal, through leftbiased contact 4! of relay MR2, conductors H6 and III, and the winding of the relay FSZ back to the negative supply terminal. As long, however, as the contact of master relay MR2 occupies its-right-hand position, selector relay F82 also remains unactuated.

Accordingly, whenever master relay MR! is following a trackway code, the spaced pulses of energizing current supplied to the first selector relay FSI through the circuit first traced above act to maintain the contacts of that selector relay continuously in their picked-up positions, this uninterrupted actuation being made possible by the before mentioned slow releasing characteristics of the relay. Once effected it continues as long as code following operation on the part of relay MRI continues.

When thus picked up, contacts 48 and 45 of relay FSI establish the earlier mentioned con nection of the decoding transformer DT with the primary supply conductors 52 and 53, contact 43 of master relay MRI then pole changes the direct current supply circuit for the primary winding-of transformer DT, and the decoding relays DR now selectively pick up in accordance with whether the'trackway-energy which operates master relay MRI is of the 80, I20 or I coding. Under such conditions, the'contacts B3 and E4 of these de coding relays complete the energizing circuit for one or another of lamps A, 50, 15 and 5 of the cab signal CS.

Likewise, whenever the master relay MR2 is following a trackway code, as when the energy supplied by the apparatus of Fig. 1 has a carrier wave frequency of 200-cycles per second, the second selector relay F82 maintains its contacts continuously picked up in response to the spaced pulses of energized current which then are received by its winding. Under these conditions, contacts I23 and I24 of relay F52 connect the decoding: transformer DT to the supply conductors H6 and H8 which are controlled by the master relay MR2, andthe direct current supply circuit for the primary winding of transformer DT now is pole changed by the contact 41 of relay MR2 in a manner comparable to that previously explained in connection with relay MRI.

That'is, when contact 41 of the master relay MR2 occupies its right-hand or energy off position, current flows downwardly through the upper half of the transformer primary by way of a circuit which extends from the positive supply terminal, through the right-biased contact 4'! of relay MR2, conductor H8, front contact 123 of relay F82, conductor l2l, the upper portion of the transformer primary and the mid tap 5! to the ne ative supply terminal. When, however, the above referred to contact l! is biased to its lefthand or energy on position, current flows upwardly through the lower half of the transformer primary by way, of a. circuit which may be traced from the'positive supply terminal, through the left-biased contact 41, conductor H6, front con.- tact l24- of-relay FS2, conductor l22, the lower portion of the transformer primary, and the mid tap 5| back to the negative supply terminal.

From the foregoing it will be seen that whenthe decoding transformer DT receives pulses of primary current which are pole changed at code frequency by master relay MR2 in response to 200 cycleenergy in the trackway, the action of the decoding relays DR is exactly the same as when these relays are controlled bymaster relay MR! in response to cycle trackway energy. In both instances the primary current pulses induce in the decoding transformer secondary an alternating currentvoltagehavingrafrequency which is the same as that of the trackway code which initiated the pulses. Regardless, therefore, of

whether this secondary voltage results from codcd' trackway energy of the 200 cycle carrier wave frequency or of the 100 cycle frequency, it supplies actuating current to the decoding relays DR through the previously described frequency selective circuits 54 and in either instance relay DRH responds to coded energizing pulses determined by all three of the named 80, and 18d trackway codes, relay DR! 29 responds only to pulses determined by the 120 code, and relay DRIZO responds i only to pulses determined by the code.

If desired, the selector relays FSI and F82 of the train carried equipment of Fig. 4 (and of Figs. 7 and 9 also) may also be rendered selectively responsive to code following operations on the part of master relays MR5 and MR2 by use of energizing circuits of the modified form represented in Fig. 5. In the scheme of that figure, the direct current winding of each of the named selector relays is connected with the secondary winding of a transformer 252 through the medium of a rectifier 243. The primary winding of this transformer is, in turn, connected across the conductors of the pole changing circuit which the associated master relay MR controls and is also provided with a mid tap 24d joined to the negative terminal of the direct current source from which the transformer DT of the decoding apparatus is energized through the master relay contacts 41.

As long as the master relay is inactive, unvarying current flows through one of the primary halves of the transformer 242 and no energy is by it transferred to the controlled selector relay FS. Under such conditions that relay accordingly remains unactuated. In the event, however, that the master relay is following a trackway code, the transformer primary receives code frequency pulses of direct current which induce an alternating voltage of the same frequency in the secondary. Through rectifier 2&3, that voltage energizes the winding of the selector relay and causes it to pick up its contacts. The circuits shown being'untuned, selector relay FSI thus responds to 100 cycle trackway energy of all three of the 80, 120 and 180 codes and selector relay FS2 likewise responds to 200 cycle train control energy of all three of the named codings.

Further considering now the added cab signal CSa of Fig. 4, it is there shown as being provided with but a single lamp 35. To facilitate description it will be assumed that when lighted this lamp displays the character by which it is marked and that the resulting signal aspect is interpreted by the engineman to mean that the maximum permissible running speed is 35 miles per hour. In the illustrative arrangement represented, this signal CSa i-s-controlled by contacts 63 and 64 of the decoding relays DRIZO and DRlBB through a circuit which is routed. through transfer contacts l26l27 and l28|29 of the selector relays FSI and F82.

Current for lighting the signal lamp 35 is supplied by way of this circuit from the same direct current source as energizes the lamps of the main cab signal CS. This lamp energizing circuit is set up by the transfer contacts just referred to whenever the selector relay PS2 is picked up and relay PS1 is dropped out, as when coded 200 cycle control energy is being received from the trackway and is completed by the actuation of decoding relay DRI20 and the dropping out of relay DRI80, a positional combination which takes place when the received trackway energy has a carrier wave frequency of 200 cycles per second and is coded at I5 and85 ofirel'ay P50) then is connected across.

the rate of 120 supply circuit interruptions per minute. The circuit extends from the positive supply terminal, through'back contact 63 of relay DRI 80, front contact 63 of relay DRI 20, conductor I2, back contact I26 of relay FSI, conductor I30, front contact I21 of relay FSZ, conductor 121), the lamp 35, conductor 16b, back contact I28 of relay FSI, conductor I3 I, front contact I29 of relay FSZ, conductor Ilia, front contact 54 of relay DRI20 and back contact 64 of relay DRI80 back to the negative supply terminal. 7 v

The energizing circuit for lamp 50 of cab signal I CS, completed under conditions of 100 cycle trackway energy reception, is carried through transfer contacts I25-I33 and I34-I29 of the selector relays PSI and F32. This circuit is set up by the contacts named when relay FSI isactuated and relay PS2 is unactuated'and is completed when decoding relay DRI20 is actuated and relay DRI80 is unactuated. It may be traced from the positive supply terminal through back contact 63 of relay DRI 80, front contact 63 of relay DRI20, conductor I2, front contact I25 of relay FSI, conductor I32,

back contact I33 of relay PS2, conductors 12d and I4, the lamp 50, conductor I6, front contact I34 of relay FSI, conductor I35, back contact I29 of relay F82, conductor 1611, front contact 64 of relay DRI20 and back contact 64 of relay'DRI00,

constitutes a precaution which safeguards against,

the giving of false indications on the part of the cab signal lamps in the .event of improper relay operation.

The added acknowledging relay P35 associated with the lamp of cab signal CSa is represented as being a duplicate of the slow releasing acknowledging relays P5, PI5 and P50 which are associated with the lamps of the signal CS." It aids in controlling the whistle W and causes it to supplement the visual indication given by the,

signal CSa whenever a change involving that indication is in the more restrictive or speed reducing direction;

In the particular arrangement of acknowleedging relays shown inFig. 4-, relay P35 is included between relays H5 and P50 in the actu ating sequence previously described and its pick upfand stick windings 85 and 31 are energized through circuits comparable to those already described for relays P5-I5- 50. That is, the pick-up circuit for this added relay P35 is completed by contact 84 of relay PI5 when picked up while the stick circuit therefor is completed when contact 88 of relay P35 is picked 'upif added cab signal lamp 35 is at that time energized over conductor 12b. i

The operation of the five indication acknowledging equipment shown in Fig. 4 will now be explained. Normally, as has been pointed out, the warning whistle Wremains inactive by virtue of its silencing circuit being completed through front contacts I5 and 85 of relay P50 and blade 46 of the acknowledging switch. If signal lamp A is lighted, all of the relays P5--I5--35-50 are dropped out and the whistle silencing circuit (previously described as including back contacts the lamp energizing conductors I8 and'8I.. If, however, any one of the remaining lamps'50, 35, I5 and 5 is lighted, the acknowledging relay P50 is picked up and the silencing circuit then is energized from the positive and negative supply terminals shown as being connected to the front points of contacts I5 and 85.

If lamp A, assumed originally to beactive (reacknowledging switch -40, preparatory to v silencing the whistle, first picks up relay P5 over a circuit which extends from the positive supply terminal, through conductors 9I and 94, the switch blade 45, conductor 35, the relay winding 81 and conductor 90 back to the negative supply terminal.

Relay P5 then picks up relay PI5 over a circuit which extends from the positive supply terminal, through conductors 9| and 94, front contact 84 of relay P5, conductor 93, winding 86 of relay P15 and conductor 90 back tothe. negative supply terminal. Relay PI 5, in turn, now picks up relay P35 over a circuit which extends from the positive supply terminal, through conductor 9|, front contact 34 of relay PI5, conductor I3'I,the winding 86 of relay P35 and conductor 90 back to the negative supply terminal. Finally, relay P35 picks up relay P over a circuit which extends fromthe positive supply terminal, through conductors BI and 54, front contact 84 of'relay P35, conductor 91, the winding 86 ofrelay P50 and conductor 90 back to the negative supply terminal. I

Relay P50 locks itself in over a stick circuit which may be traced from the positive supply terminal, through back contact 63 of relay DRI80, front contact 63 of relay DRI20, conductor I2, front contact I26 of relay FSI', conductor I32,

back contact I 33 of relay FSZ, conductors 12a and I4, front contact 88 of relay P50, conductor 98 the winding 3! of that relay and conductor 90 back to the negative supply terminal. Contacts 15 and of relay P50 now connect the whistle silencing circuit directly with the associated positive and negative energizing supply terminals.

This circuit is completed and the whistle silenced when blade 45 of the acknowledging switch returns to its upward or normal position. At that I relays FS, and once more places the whistle W in operation. As the acknowledging, switch 45-48 is depressed, relays P5 I5-3550 are again picked up in order. Relay P35 locks itself in over a stick circuit which extends fromthe positive supply terminal, through back contact 63 of relay DRIfiil, front contact 63 of relay DRI20, conductor "I2, back contact I26 of relay FSI, conductor I30, front cont-act I21 of relay Fslconductor 12?), front contact 88 of relay P35,

conductor I39, the winding 87 of relay P35,'and conductor 99 back to the negative supply terminal. Contact 84 of relay P35 maintains relay P56 picked up and the contacts 15 and 85 of that relay now connect the whistle silencing circuit directly with its special energizing terminals. This circuit is completed and the whistle silenced when the acknowledging switch returns to its normal position. At that time relays P and P55 drop out.

If lamp 35 goes out and lamp I5 is lighted (relays FS 2 D RH picked up;

FSZ--DR 2El-DRi 8e} dropped out) ,relayP5ii once more drops out, as a result of the stick circuit for relay P35 having been interrupted at contacts 3 3 2'27 of the selector relays and atcontact 83 of relay DRIH, and again places the tie W in operation. As the acknowledging ch depressed, relays P5I5-35-5ii are once more picked up in order. Relay PI5, now looks itself in by connection, through its own contact 88 and conductor 99, with the conductor if. over which lamp I5 is energized. Its contact 84 maintains relay P35 picked up which, in turn, holds relay P59 picked up. Contacts and 85 of that relay now connect the whistle silencing circuit with its energizing terminals. This circuit is completed and the whistle silenced when the acknowledging switch returns to its normal position, at which time relay P5 drops out.

Finally, if lamp I5 goes out and lamp 5 is lighted (relays FS IFS2DRHDRI DR I 80 dropped out), relays Pl535--5fi drop out in the order named, as a result of the stick circuit foruelay PIE having been broken at contact 63 of relay DRH, and the whistle is again placed in operation. As the acknowledging switch is depressed, relays P5I5-3550 are again picked up in order. Relay P5 now looks itself in by a connection of its winding 81, through its own contact 88, with the conductor 61 over which the lamp 5 is energized, and thus holds the re-- maining acknowledging relays also picked up. Contacts '15 and 85 of relay P50 then cooperate with the acknowledging switch, when returned to its normal position, to discontinue action on the part of the whistle.

Changes of cab signal indication in the speed increasing or less restrictive direction do not, as has been mentioned, bring the warning whistle into action. Each indication change of this character is accompanied by the completion of the stick circuit for the next relay P above the associated one in the acknowledging sequence and all of these relays are sufficiently slow releasing as not to drop out during those short intervals of time in which the decoding relays DR and the selector relays FS shift their contacts from one position to the other in effecting indication changes. Upon the occasion of each less restrictive change, therefore, only the relays below the associated one in the acknowledging sequence are allowed to drop out while all those above it are maintained picked up until .a more restrictive indication takes place.

The various component parts of the first embodiment of my improved cab signalling apparatus having been described, attention will now be directed to the manner in which this complete system of Figs. 1 and 4 operates to provide five distinctive indications aboard a locomotive or other train vehicle.

Assume first that all of the sections of the protected stretch of track represented at I-2 in Fig. 1 are unoccupied. Under such a. condition the track relay TR at each wayside signal location D, E, F, etc. is picked up, the approach relay AR at each of these locations is dropped out and the rails of each of the sections are supplied with uninterrupted 100 cycle energy. Assume next that a ,train propelled by a locomo tive equipped with the apparatus represented in Fig. 4 proceeds through the stretch of track protected by the apparatus shown in Fig. l.

The wheels and axles of this train shunt the track-way potential from between the rails of each occupied section and cause the track relay TR associated with that section to drop out. At the exit end of the section approach relay AR now places the code transmitter CT in operation, disconnects the track transformer 'I'T from its steady energy supply circuit, and sets up a coding circuit therefor with BC as the supply source. The several advance track sections being vacant, all of the traffic governing relays H, J I and J2 at the next signal location ahead of the train are picked up, contacts 29 thereof include the coding contact I86 in the supply circuit for the associated track transformer TT, this transformer impresses 100 cycle energy of the i8!) coding between the rails of the occupied section at the exit end thereof, and current of a corresponding character now circulates through the portions of those rails which are ahead of the equipment-carrying vehicle.

On this vehicle, this 100 cycle track circuit current of the I88 code induces corresponding voltages in the pick-up windings 3'! of the ceiver and filter QI passes a measure of these induced pulses of 100 cycle voltage to amplifier 48 which delivers code following energy to master relay MRI. Filter Q2, however, prevents the named voltages from reaching the amplifier 40a which is associated with the second master relay MR2. Under the control of code following relay MRI selector relay FSI picks up and connects decoding transformer DT to the pole changing circuit of relay MRI. Transformer DT now supplies energy which picks up decoding relays DRH and DRI8D and these relays complete the lighting circuit for lamp A of cab signal CS. The resulting signal aspect indicates to the engineman that the train may proceed at unrestricted or full authorized speed. As the train comes into a section, such as that shown at DE in Fig. 1, containing a curve or other permanent speed restriction, the trackway apparatus supplies the rails with 200 cycle energy derived from sources B2C2 and coded at the 120 rate. This comes about when relay TR at location D drops out and picks up relay AR at location E thereby placing the associated code transmitter CT in operation, connecting transformer 200T with source B2C2 and periodically connecting track transformer T1 to transformer 280T through the coding contact I26.

On the train within section D-E, the picked up measure of this 200 cycle trackway energy of the I20 code is passed by filter Q2 to amplifier 46a, which, in turn, supplies code following energy to master relay MR2. Filter QI now prevents this 200 cycle potential from reaching amplifier #0 and thus prevents master relay MRI from operating. In following the trackway code, contact 41 of relay MR2 supplies actuating energy to selector relay FSZ which picks up its contacts connecting decoding transformer DT to the supply circuit controlled by relay MR2 and transferring the control of decoding relays DRlZi! and DRI30 from lamp 50 of cab signal CS to lamp ran av 35 of added signal CSa. Transformer DT now suplies energy which picks up relays DRH and DRIZIJ, and these relays complete the lighting circuit for cab signal lamp 35, which, in turn, advises the engineman that 35 miles per hour is the maximum safe speed permissible.

As the train leaves section DE and advances into another section, such as E-F, which contains no curves or other permanent speed restrictions, it again encounters 100 cycle trackway energy of the I80 code which causes lamp 35 of cab signal CSa to be extinguished and lamp A of signal CS again to be lighted.

Upon departure of the train from section D-E the rails thereof transmit 200 cycle energy from the transformer IT to the control winding of the track relay TR at location D, winding 6 of that relay receives energy of identical character through line conductor I05, and the relay picks up and breaks the actuating circuit for relay AR at location E. That relay now drops out, shuts down the code transmitter CT, disconnects transformer 200T from source B2--C2 and reconnects the track transformer TI directly with the 100 cycle supply source B-C. Until another train comes into the section DE, track relay TR at location D is maintained actuated by this uninterrupted 100 cycle energy which is supplied to both windings of the relay by way of the track rails and line conductor H15 respectively.

Assume now that while proceeding through territory having no curves or other permanent speed restrictions the cab signal equipped train closes in on another train ahead which also is going along track equipped at each wayside signal location with apparatus which is a duplicate of that shown at D and F in Fig. 1.

As the train carrying the apparatus represented in Fig. 4. comes into the second track section behind that occupied by the advance train, the rails of that section receive 100 cycle energy of the I code. This is because traffic governing relays J! and J2 at the exit end of that section are both dropped out due to their energizing circuits being broken by the track relay TR at the entrance of the advance occupied section. Contact 29 of relay J I now includes coding contact I20 of transmitter CT in the primary circuit of the associated transformer TT and this circuit is connected with 100 cycle source B-C as soon as approach relay AR picks up in response to the entry of the signal carrying train into the section in question. On the train this energy causes relay MRI to follow the code, relay F8! to be picked up, and relays DRH and DRI20 also to v be actuated. Lamp 58 is accordingly lighted to indicate that the maximum safe running speed is 50 miles per hour.

As the signal equipped train comes into the first track section behind the one occupied by the advance train the rails of that section receive 100 cycle energy of the 80 code. .This results from all of the traiiic governing relays H, J I and J2 at the exit end of the rear occupied block dropping out as a result of their actuating circuits being broken by the track relay'TR at the entrance end of the advance occupied section. Contact 29 of relay H now includes coding contact 80 of transmitter CT in the primaryv winding circuit of the associated'track transformer TI. This circuit is connected with source B-C when approach relay AR picks up its contacts upon the entry ofthe signal equipped train into the sectionin question. On this train thelOOcycle 80 code energy received from the trackway causes master relay MRI to operate, selector relay FSI to be actuated, decoding relay DRI-I to be picked up and cab signal lamp [5 to be lighted, thereby indicating that the maximum safe speed is 15 miles per hour.

If now the train in the rear advances into the rear portion of the block through which the train ahead is traveling, no energy at all will be present in the portions of the rails which are immediately ahead of the rear train, due, of course, to the by-passing action of the wheels and axles of the advance train. On the signal equipped train in the rear both of the master relays MRI and MR2 accordingly remain inactive, selector relays PSI and PS2 are dropped out, the decoding transformer DT is deenergized and all three of the decoding relays DR likewise are dropped out. Under these conditions, the energizing circuit for lamp 5 of cab signal CS is completed and that lamp lights to indicate that the maximum safe running speed is 5 miles per hour.

The foregoing description of the operations which take place when the cab signal equipped train approaches sufiiciently close to another train ahead to require that its speed be reduced to 15 or 5 miles per hour apply not only to track sections, such as E-F of Fig. 1, the equipment of which responds to advance occupancy conditions only, but also to the section D--E containing the curve or other permanent speed restriction with which the assumed limit of 35 miles per hour has been identified.

Thus when the signal carrying train is within section DE and the next section immediately ahead, or EF, is occupied, the track relay TR at location E is dropped out and all of the traffic governing relays H, J l and J2 are also dropped out. Contact 29 ofrelay I-I now includes coding contact 80 of transmitter CT in the primary cirpresence of the train within the section DE now places the transmitter in operation and thereby causes 100 cycle energy of the 80 code,

to be supplied to the rails of section DE.. On

the train, this causes lamp i5to light in the manner already explained. Likewise, when therear portion of the advance train is in the exit end of section DE and shunts the energy from transformer TT from between the rails, the rear or signal carrying train responds to the absence of this energy by causing lamp 5'to light, also in the manner previously explained.

As the manner in which the warning whistle W, the acknowledging relays P and the acknowledging switch 46 function under all more restrictive changes of cab signal indications has previously been. explained rather fully, no further description of the operation of those portions of the improved cab signalling system disclosed in Figs. l-4 need here be given.

Seven indication system of Figs. 6-7

The seven indication system of cab signalling disclosed in Figs. 6-7 is basically similar to the just described five indication system of Figs. 1-4. It incorporates the apparatus of, and is built around, the conventional four indication system described in the first part of this specification as operating on coded energy of a single carrier wave frequency, assumed to be 100 cycles per second and shown as being derived from source BO. Likewise, the seven indication system now about to be described also makes use, under certain conditions, of trackway energy of a second or additional carrier wave frequency, again assumed to be 200 cycles per second and shown as being derived from source B2C2.

Whereas, however, the system of Figs. l-4 codes this second frequency energy at but the single rate of 120 supply circuit interruptions per minute and thereby operates only one added cab signal lamp 35, the trackway portions of the system of Figs. 6-7 include provision for coding the second frequency energy at any one of the three rates of 80, 120 and 180 interruptions per minute and the train carried portions of this system likewise includes three added lamps 25, 35 and 60, re spectively arranged to respond to energy of the three distinctive characters just named. As will be seen,- a total of seven indications is in this manner made available.

In the illustrative arrangement of trackway apparatusshown in Fig. 6, the and 180 codings of the second frequency or 200 cycle energy correspond to two added speed indications, while the 120 coding of this energy is identified with a curve indication analogous to that described in connection with track section DE of Fig. 1. As represented, this curve (which again typifies perrnanent speed restrictions of all kinds) is within the confines of block K-L and the two added speed indications just referred to are included in an extended arrangement of the illustrative form of automatic block signalling equipment which has previously been described generally and the special features of which will now be considered.

In Fig. 6, each of the waysidesignals Sic and SZ, and so on, has a total of five semaphore arms which provide aspects of a meaning previously explained. That is, elevation of the uppermost arm signifies that the track section immediately ahead of the signal location is clear; elevation of the second arm from the top indicates that there are two clear track blocks ahead; elevation of the third arm shows that three blocks ahead are clear; elevation of the fourth arm shows that four blocks ahead are clear; and the elevation of the fifth or bottom arm signifies that the five blocks immediately ahead of the signal are unoccupied.

For controlling each of these signals a total of five traflic governing relays H, J I, J2, J3 and J4 are provided. Each of these relays is associated with one of the signal arms, it causing that arm to be elevated when the relay is actuated and allowing the arm to occupy its downward or traffic restricting position when the relay is dropped out. In the manner represented and already explained, the actuating circuits for the trafiic governing relays are carried through the contacts of the associated and advance location track relays TR. Thus, when the section immediately ahead of a particular location is occupied all of the traffic governing relays at that location are dropped out; when there is but one vacant section ahead relay H only is picked up; when there are but two vacant sections in advance relays H and J I are picked up; when there are but three vacant sections ahead relays H, J I and J 2 are picked up; when there are only four vacant sections ahead relays H, J I, J2 and J3 are energized; and finally, when five or more sections ahead of the location are unoccupied all five of the traffic governing relays are picked-up.

In the case of all of the track sections of the wayside system of Fig. 6, the contacts 29 of the traffic governing relays select which one of the the wayside signals S signify that the five bIocks 'IO in advance of each signal areclear, all of the approach relays AR are dropped out and source B--C supplies steady cycle energy to the rails of each section. Under these conditions the of the approach relay AB, conductor 8 and the associated track transformer T1. When, however, a train occupies one of these sections the track relay TR at the entrance end thereof drops trackway supply circuit includes back contact 'I l-i out, the approach relay AR at the exit end picks'" up, the associated code transmitter CT receives operating energy through the front contact 26 of that relay, and the transformer 200T is connected by contacts I02 and I04 to supply source B2-C2.

If four or more sections ahead of that exit end location are vacant, as reflected by the there installed traffic governing relays I-I, JI, J2 and J3 being energized, source BC supplies the rails of the track section in question with I00 cycle energy of the I80 code. the track transformer T1 and by way of a primary energizing circuit which extends from supplyterminal B through front contact I of relay AR, conductor I 00, front contacts I3 of relays J3, J2, J I and H in series, conductor 28, coding contact I80 of transmitter CT, conductor 32, front contacts 29 of relays J2, J I and H in series, conductors 3| and 8 and'the primary of transformer TT back to supply terminal C.

If only three track sections ahead of the occupied one under discussion are vacant, as reflected by traffic governing relay J3 being unactuated, source B2-C2 supplies the rails of that section with 200 cycle energy of the I80 code. The track transformer energizing circuit may now be traced from one side of the secondary of transformer 200T through conductor I03, back contact I3 of relay J3, front contacts I3 of relays J2, J I and H in series, conductor 28, coding contact I80, conductor 32, front contacts 29 of relays J2, 'J I and- H in series, conductors M and 8,-the primary winding of transformer TT, and conductor-I06, back to the other side of the secondary of transformer 200T.

If only two track sections ahead of the occupied one are vacant, as reflected by traffic governing relays J2 and J3 being unactuated, source B-C supplies the rails of that section with 100 cycle energy of the I20 code. The track transformer energizing circuit now extends from supply tera;

minal B through front contact I of relay AR, conductors I00 and I40, back contact I3 of relay J2, front contacts 13 of relays J I and H in series, conductor 28, coding contact I20 of device CT, conductor 33, back contact 29 of relay J 2, front con tacts 29 of relays J I and H, conductors 3| and 8, and the primary of transformer TT back to supply terminal C.

If only one track section ahead of the occupied one is vacant, as reflected by relay H only of the traific governing group being actuated, source B2-C2 supplies the rails of that occupied section with 200 cycle energy of the 80 code. The track transformer energizing circuit may now be traced from one side of the secondary of transformer:

This supply is through 

